Aircraft icing poses a critical threat to civilian and military fixed-wing aircraft and rotorcraft, particularly when this icing occurs on engine inlets, control surfaces, windshields, rotor blades, and wing leading edges. The hazards of icing arise in several forms including direct concerns such as altered aerodynamic properties, the obstruction of flaps and other mechanical systems, and mass imbalance, as well as indirect concerns such as decreased controls sensitivity, shedding, excessive vibration, and increased power demands. Any one of these complications could potentially lead to an accident.
A wide variety of ice detection systems are currently being utilized or have been utilized for in-flight ice detection in the past. The ice detection methods employed by these systems include external vibrating probes, radioactive probes, fiber optic sensors, temperature probes, electrical resistance or impedance measurements, piezoelectric vibration sensors, differential air pressure detectors, RF transmission line sensors, combined thermal and electrical external measurement probes, acoustic cavity resonators, traditional ultrasonic bulk wave sensing systems, and several ultrasonic guided wave ice sensing systems. Each of the existing ice detection technologies have inherent disadvantages including, but not limited to, insufficient sensitivity, high cost, false alarms due to contamination, hazardous materials, and limited sensing area.